1. Field of the Invention
The present invention relates to a wide-band reproducing speaker which can reproduce a very high range of frequencies up to 70 kHz, for example.
2. Description of the Related Art
In general, a whole band speaker having a small aperture (diameter), for example, an aperture of 39 mm, is constructed in a manner that a voice coil bobbin is attached to an inner circumferential portion of a diaphragm comprising a paper cone while a voice coil is wound around the voice coil bobbin, and the voice coil is inserted into a magnetic gap. However, in the above speaker, it is difficult to reproduce a very high range, and further, a reproducing range by the speaker is up to 40 kHz to utmost because a weight of the voice coil is heavy.
The present invention has been made in view of the above problem. It is, therefore, an object of the present invention to provide a cone type speaker which can reproduce a very high range up to 70 kHz, for example.
To achieve the above object, the present invention provides a speaker which is constructed in a manner that a voice coil bobbin is attached to an inner circumferential portion of a cone type diaphragm while a voice coil is wound around the voice coil bobbin, and the voice coil is inserted into a magnetic gap, characterized in that the voice coil bobbin is formed of a conductive material while the voice coil being fixed to the voice coil bobbin by a soft bonding agent, and in a very high range, the voice coil is operated as a driving coil while the voice coil bobbin being operated as a short coil.
According to the present invention, in low, mid and high ranges, a diaphragm comprising a cone paper is driven by the voice coil like an ordinary speaker up to 40 kHz. In the present invention, the voice coil is fixed to the voice coil bobbin by a soft bonding agent; therefore, in a very high range of voice, a bonding strength of the soft bonding agent lowers. As a result, the voice coil bobbin and the voice coil become a state of separating from each other, and then, constitutes an electromagnetic induction type speaker such that the voice coil is operated as a driving coil while the voice coil bobbin formed of a conductive material being operated as a short coil. Thus, the diaphragm is driven by a vibration of a very light voice coil bobbin, and the voice coil before separating from the voice coil bobbin has no mass, and therefore, by a difference in mass, it is possible to reproduce a very high range up to 70 kHz, for example.